Reverse remodelling induces progressive ventricular resynchronization after cardiac resynchronization therapy 'from vicious to virtuous cycle'

AIMS: Cardiac resynchronization therapy (CRT) can stop the vicious cycle resulting from dyssynchrony and generates left ventricular (LV) reverse remodelling. Our objective was to assess the time course and the relationship between improvement in LV dyssynchrony and reverse remodelling after CRT. METHODS AND RESULTS: Sixty-four consecutive patients were evaluated before, immediately after, and 3- and 6 months after CRT. We measured LV volumes, ejection fraction (EF), and sphericity index, and dyssynchrony was assessed using speckle-tracking radial strain. Response was defined as a >15% decrease in end-systolic volume (ESV) 6 months after CRT, and event-free survival was followed for 24 months. Responders and non-responders had similar baseline LV volumes and EF. During the first and the following 3 months after CRT, LV volumes gradually decreased (end-diastolic volume: 195±73 to 164±60* to 129±51 mL†, ESV: 141±70 to 110±47* to 82±40 mL†), and sphericity index and EF progressively increased (sphericity index: 1.52±0.20 to 1.75±0.31* to 1.94±0.34†, EF: 28±7 to 34±7* to 38±8%†, *†P<0.001) in responders. No such changes were observed in non-responders. Furthermore, dyssynchrony diminished progressively during the first and the following 3 months after CRT and patients with progressive resynchronization experienced fewer major cardiovascular events than those without (P<0.001). CONCLUSION: CRT can stop the vicious cycle of remodelling and dyssynchrony, and actually, turn it into the virtuous cycle of reverse remodelling and further resynchronization.